Effect of Zr/Ti ratio on the properties of PMMN-PZT ceramics near the morphotropic phase boundary

Pb(Mg1/3Nb2/3)O-3 -Pb(Mn1/3Nb2/3)O-3-Pb(ZrxTi1-x)O-3 quaternary piezoelectric ceramics with varying Zr/Ti ratio, which locate in the vicinity of the morphotropic phase boundary (MPB), were prepared. The phase structure, the piezoelectric and dielectric properties of the system were investigated. X-ray diffraction patterns indicate that the MPB of the tetragonal and rhombohedral phase lies in the range 0.49 < x < 0.52. Both the piezoelectric coefficient (d(33))/electromechanical coupling factor (K-p) and the dielectric constant (epsilon(r)) reach the maximum values at x = 0.50. The changes of resonant frequency with increasing Zr/Ti ratio are from a positive to a negative value and obtained a minimum value at x = 0.50, which reflects the transition from tetragonal phase to rhombohedral phase. (C) 2002 Elsevier Science B.V. All rights reserved.